Aerator



AERATOR Filed Dec. 24, 1934 A. C. DURDIN. JR

Dec. 8, 1936.

J I fl Patented Dec. 8, 1936 PATENT OFFICE summon Augustus O. Dlirdin, In,

signor to Chicago Pum a corporation of Illino Application December 24,

13 Claims.

This invention relates to aerators and its principal object is to impregnate liquids with air or gas. In the treatment-of liquids'for certain purposes, abundantquantities of oxygen or other gas are supplied thereto and various attempts have beenmade to accomplish this result with more or less success. In the activated sludge process of treating sewage, aerobic bacteria are used, and in this process it is necessary to supply the bacteria with abundant quantities of oxygen.

' other liquid and One object 'of this invention is to provide a simple and highly eflicient aerator, operating to supply abundant quantities of air to sewag or desirably composed of a single unitary structure. I

Another object is to lift or propel sewage or. other liquid from an upright conduit and discharge the same therefrom in the form of a hollow' column impregnated with air, whereby the aerated sewage or other liquid discharges uniformly in all directions from the conduit.

Other objects andadvantages will appear in the course of the following specification and with said objects and advantages in view, this invention consists in the several novel features hereinafter fully set forth and claimed.

The invention is clearly illustrated in the ac-- companying drawing, in which:

Fig. 1' is a view, partly in side elevation and partly in vertical section of aerating apparatus equipped with an aerator embodying a simple form of the present invention;

Fig. 2 is a plan of the aerator;

Fig. 3 is a view, partly in plan and partly in horizontal section taken on the line 33 of Fig. 4, and

Fig. 4 is a side elevation of the aerator.

Referring to said drawing, the reference character Ill designates an electric motor or other prime mover, mounted on a bridge structure II, and provided with a shaft I2 dependingtherefrom. Thebridge or platform is usually placed above a tank (not shown) for containing the .liquid to be treated and in the tank is an upright,

open ended, conduit, a fragment of which is seen at l3. In some instances a splash platform [4 extends from the upper end of the conduit, and the aerated liquid is splashed upon said platform by the aerator and discharged therefrom into the liquid contained in the tank. The parts described are now common and well known and require no further description so far as this specification is concerned. a

Keyed or otherwise rigidly mounted-upon the Niles Center, 111., 88-

%Wmpany, Chi ago, 11-,

1934', Serial No. 159,043

shaft I2, within the conduit I3, is the aerator, designated generally by the character A. It is formed with a body or hub I 5 by means of which it is mounted on the shaft, and projecting radially therefrom are several propeller blades I6 5 of conventional form. Desirably each blade has a leading or entering edge I1 extending from the face of the lower end of the body I5 in an inclined direction along a non-concentric curved line, somewhat in the nature of an involute 10 curve. At the outer extremity of each blade the curved edge is carried back and around to the rear of the blade where the receding edge I8 is reversely curved and merges into the body portion. Each blade is pitched upward in a direction opposite to the direction of rotation of the impeller whereby to thrust the liquid in a direction approximately parallel with the axis of the impeller, or more specifically, in an upward direction. The exact shape of blade described is taken for the purposes of illustration only, and it is to be understood that I do not limit my invention to the particular shape shown and described. This form of blade, however, has been found in actual practice, to be highly efllcient for 2 the purpose intended, since the thrust isupward, with very little centrifugal action on the liquid.

- At or adjacent the upper end of the body is a liquiddefiecting element I9, here shown as comprising an annular flange or web that projects from the body. Desirably the deflecting element I9 is located at or slightly below the highest point of the propeller blades. As shown the deflecting element is flat on its underside, but not necessarily so, and its radius is considerably less than the radius of the propeller blades. The deflecting element assists in directing radially outward that part of the upwardly moving column of liquid below the deflecting element, whereby the liquid is thrust upwardly above the aerator by 4 the propeller blades in the form of a hollow col umn of liquid.

Between the propeller blades and deflecting element l9 are impeller blades 20 the impelling faces of which project tangentially from the cylindrical face of the body or hub I5 of the aerator part way across the propeller blades and serve to impart a centrifugal action to that part of the liquid which the propeller blades thrust upward in their path of rotation, thereby throwing liquid into the hollow column of liquid passing the impeller blades. The working faces 2I of the impeller blades 20 are straight or slightly curved, but they may take various desirable shapes that are designed to impart centrifugal action to the ing faces of the impeller blades,'propeller blades and deflecting element are joined by fillets or rounded corners. 1 j

The deflecting element i9 'also carries fan blades 23, which as shown project radially inward from the marginal edge-of the deflecting element,

on the upperside thereof, thus providing a fan. or blower operating to force air' into the vacuumzone at the tips of-theimpeller.bladesanddnto; the rolling, turbulent ,hollowcolumn of liquid a cap 29. An upper bearing cap 34 closes the upper .end of the housing. Oil or grease is supplied to the. bearings inany desirable manner.

surrounding and passing by. the fan..

In operation, the aerator is tated at high" speed. The propeller hlades-picltupand thrust the liquid upward at great'velocityjcausing more or less of a turbulent condition therein. The inner part of the movingcolumn of liquid is caught below the deflecting element greater turbulent condition therein an'dz'tending to prevent the hollow column-'ofgliquid from-clos ing in around the aeratorshaft and'at ttie same. time, the fan blows airi'into the vacuum'zo'nes. and into the turbulent hollowystream, ftherebyf effectively supplying anair thereto. The general direction of movement abundant. quantity of is upward and slightly outward, whereby as its momentum slows down, it tumbles down upon the platform outside the conduit. It will be understood that air is free to descend through the hollow of the stream to the fan. 7

Although the general direction of movement of the hollow column of liquid is approximately parallel with-the axis of the propeller, the liquid takes a path somewhat in the nature of a helix, winding or circling upward from the propeller. The liquid thrown into the hollow column by the impeller blades appears to take a circling path in upward directions, in the helically moving column (see dotted lines in Fig. 1). As a result the internal surface of the hollow column of liquid is constantly changing, new surfaces are constantly being exposed to the air in the hollow of the column and as these changing surfaces become exposed'to the air they absorb air and roll the air into the liquid. Owing to the multiplicity of the hollow stream of constantly changing surfaces of the liquid that are exposed to the air, a greater amount of air is carried into the liquid than heretofore.

In my experiments I have found that the fan may be omitted and good results obtained. For many purposes the deflector may be dispensed with and the impeller blades may be omitted, but when the deflector is used it is preferable to employ walls between the propeller blades and deiiector to prevent solid or semi-solid matter from being caught between the propeller blades'and the deflector, when large propellers are used, the efficiency of the aerator is increased by the use of bailles 24 located directly below the propeller and preferably inclining upward at a suitable angle in the direction of rotation of the propeller.

The motor ill usually-is located at some distance above the level of the liquid in the tank, and inasmuch as the aerator A is located below the liquid level, a relatively long aerator shaft 12 is employed to connect the motor with the aerator.

by the impeller. blades and thrown outward laterallylintothe -moving' column of liquidf'thereby setting.up a

' pitched to from the body A shaft coupling 35 connects the motor shaft and aerator shaft. It is undesirable to provide a hearing for the lower end of the shaft, and consequently novel bearings are provided therefor separate from and located below the motor shaft l2. As shown a bearing housing 25 is provided around the upper end of the aerator shaft in which are contained upper and lower shaft bearings 26, 21. A flange 28 formed on the housing adjacent its upper end supports the housing, and the upper bearing 26 supports the cap 29 closes the lower end of the housing and shaft. A lower bearing "a shaft ,co'ver' tube 3li is secured to the lower end of the cap 29 and surrounds the end of the shaft that projects belomthe cap. Oil or grease seals 31, 32 are-providedat the'lupper end of the housingandan oil or grease sealS-tis provided in the 'From the above it will be seen that a long bearing, separate-from theimotor is provided for the aerator shaft-which eliminates the necessity of 'providinga 3 other reasons.- The-"shaft, coverztube, being stationary, prevents ,strings,l'rags or the likefrom l -wrapplng around theshaft, anddntezfei'lnfl with the operationofIthe aerator.

, I claim as new and desire to secure by Letters Patent:

1. An aerator comprising a body portion having propelling blades projecting therefrom propel liquid in a direction app oximately parallel to the centrifugally acting impelling elements extending transversely'with respect to the axis of the aerator, and disposed between the entering and'receding edges of the propelling blades.

2. An aerator comprising a body portion having propelling blades projecting therefrom, pitched to propel liquid in a direction approximately parallel to the axis of the aerator, and

centrifugally acting impeller blades projecting from thebody, part way .over the propelling blades and being disposed between their'entering and receding edges.

3. An aerator comprising a body portion having propelling blades projecting therefrom, and centrifugally acting impeller blades projecting portion part way across the propeller blades, the impeller faces of said 'impelling blades extending in lines tangential to the face of the body portion.

4. An aerator comprising a body portion having propeller blades projecting therefrom, pitched to propel liquid in a direction approximately parallel with the axis of the aerator, a deflecting element spaced above the blades and projecting from the body portion part way over hearing at lower; rid -91 necessary to"'ra ch theimpellerfor repairs or for axis of the aerator, and

the propeller blades and impeller blades extend- 9,068,801 mately parallel to the axis of the aerator, an annular flange projecting from the body portion part way over the propeller-blades in a plane below the highest point on the blades, and centrifugally acting impeller blades joining the propeller blades and flange.

- 7. An aerator comprising a body portion having propeller blades projecting therefrom, pitched to thrust liquid in a direction approximately par-I- allel to the axis of the aerator, a deflecting element adjacent the upper edges of' the blades and fan blades of less radial extent than the propeller blades, carried by said deflecting element.

8. An aerator comprising a body portion having propeller blades projecting therefrom, impeller blades above the propeller blades projecting part way across the same, and a fan above the impeller blades.

9. An aerator comprising a body portion having propeller blades'projecting therefrom, centrifugally acting impeller blades above the propeller blades projecting part way across the same, and a combined deflecting element and fan above the impeller blades.

10. In an aerator, liquid propelling means for thrusting a column of liquid in a direction parallel with the axis of the aerator, and impelling means joining the upper faces of the propelling means, for throwing part of the moving liquidoutward radially into the column of liquid.

column,

3 v 11. In an aerator, propelling means for thrusting a column of liquid in a direction parallel with the axis of the aerator, deflecting means for deflecting outward the inner part of the column of liquid, centrifugally acting means between the propelling means and deflecting means for throwing the inner part of the column outward into the surrounding body of liquid, and air blowing means adjacent the centrifugally acting means.

12. An aerator, comprising an open ended conduit into which liquid to be treated enters at its lower end and is discharged therefrom at its upper end, propelling means adjacent the upper end of the conduit for propelling the liquid therein upward in the form of a hollow column with its internal face contacting with air and discharging it therefrom, and means submerged in the liquid below the hollow liquid column for setting up turbulence in the rising hollow'liquid column.

13. An aerator, comprising an open ended conduit into which liquid to be treated enters at its lower end, propelling means adjacent the upper 'end of the conduit for propelling the liquid therein upwardsin the form of a hollow column and discharging it therefrom, means submerged in the liquid below the hollow liquid column for setrising hollow liquid.

ting up turbulence in the and meansfor supplying air to the internal face of the hollow liquid column.

AUGUSTUS C. DURDIN, JR. 

